The present invention relates to pipe shoes for supporting a pipe, conduit, or other elongate tubular member with a generally circular exterior surface. In particular, this invention relates to a clamp-type pipe shoe for supporting insulated or non-insulated pipe on a pipe rack in a commercial or industrial facility.
Commercial and industrial facilities, such as petrochemical plants, conventionally support process piping on a series of overhead racks each having a generally horizontal top surface. A series of generally parallel pipes are typically supported at regular intervals, e.g., 6 to 12 inches, on the pipe racks, and carry gas or liquid throughout the facility. The process piping typically is supported on pipe shoes, which in turn are supported on the pipe rack at, e.g., 20 to 30 foot intervals.
Since the process piping is supported above the pipe rack, the piping may be initially installed on the pipe shoes, and the pipe thereafter wrapped or covered with insulation to retain heat within the fluid passing through the process piping, or to minimize the likelihood that liquids in the process piping will freeze during cold weather. Pipe shoes support both the pipe and the insulation above the pipe rack, and a single petrochemical facility may utilize 100,000 pipe shoes or more to support its process piping on the pipe racks.
Pipe shoes commonly include a base and a pair of axially spaced clamps for interconnecting a generally lower semi-circular clamp fixed to the base to a generally upper semi-circular clamp, so that the connected clamps support the piping. The base may slide along the planar upper surface of the pipe rack as the process pipe expands or contracts in length. The generally lower clamp half is welded to the base, so that the weight of the pipe is supported on the generally lower clamp half. Ears project radially outward from both the lower and upper clamp halves, and a pair of conventional bolts interconnect the mating radially-opposing ears to secure the piping to the pipe shoe.
In spite of its widespread use, the above pipe shoe has significant disadvantages, particularly when used for supporting an insulated pipe. Conventional pipe insulation typically is manufactured in axially split halves sized for a particular diameter pipe. Two insulation halves are positioned about a pipe then taped or otherwise secured thereto to form an insulated sleeve of the desired thickness. Since the process pipe is supported by the pipe shoes along the rack, the insulation installer can quickly and reliably install the split insulation along the length of a given pipe between the pipe shoes. Since the radially-opposing ears project an inch or more outward from the pipe, and since the vertical bolts which interconnect these ears are spaced outward of the pipe, the pipe shoes present problems to the insulation installer. The installer typically cuts out a portion of the insulation where the clamp ears and bolts will be located, and xe2x80x9cputies overxe2x80x9d the cutout holes with a caulking material to reduce heat loss from the pipe. Apart from the increased insulation cost, this process does not adequately protect the pipe as well as the insulation. Since the projecting ears in the clamp halves act as a heat sink, they draw valuable heat from the process pipe and release the heat to the atmosphere. The caulking typically tends to deteriorate, and in time cracks and breaks away from the projecting ears, thereby leading to deterioration of the insulation.
A pipe shoe which overcame many of the problems of the prior art is the Interlock(trademark) pipe shoe, as disclosed in U.S. Pat. No. 4,858,861. More particularly, this pipe shoe reduce the time required for the insulation installer to cover the pipe. Also, the pipe shoe reduced corrosion by providing a gap between the pipe shoe and the lowest point of the pipe, thereby minimizing corrosion of both the pipe and the pipe shoe due to condensation from the outer surface of the pipe. Also, the pipe shoe facilitates the insulation of electrical heating lines or steam trace lines along an insulated pipe.
Some pipe shoes have provided a clamp exterior rather than interior to the pipe insulation. With these pipe shoes, it is difficult for the installer to place the desired and uniform radially inward clamping force on the insulation from the pipe shoe. If the pipe shoe clamping bolts are over-tightened, the insulation and/or the pipe may be damaged, e.g., when using fiberglass or plastic pipe. If the clamp shoe bolts are under-tightened, the pipe is allowed to undesirably slide within the pipe shoe during thermal expansion and contraction of the pipe. Moreover, the radially projecting clamp ears may interfere with other pipe shoes, and significantly limit the area in which the installer may safely operate.
The disadvantages of the prior art are overcome by the present invention, and an improved pipe shoe and a method of installing a pipe shoe between a pipe and a pipe rack are hereinafter disclosed.
The pipe shoe according to a preferred embodiment the present invention supports a pipe or other elongate member from a pipe rack or other structural support. The pipe shoe includes a generally horizontal base plate, and a left-side support plate and a right-side support plate each fixed to and extending generally upward from the base plate, with each support plate including a respective left-side and right-side support plate port. A curved lower plate is fixed to and supported on the left-side support plate and the right-side support plate, and is configured for supporting the elongate member. After the pipe is positioned on the curved lower plate, a curved upper plate is positioned over the pipe, with a left-side upper plate hole and right-side upper plate hole at the lower ends thereof. Due to an enlargement in one or more of the holes, a bolt is passed through the upper plate hole and the respective left-side or right-side support plate hole for receiving a bolt. When the bolts are subsequently tightened, the curved upper plate is effectively pulled downwards onto the lower curved plate, thereby providing a desired radially inward clamping force which is uniformly distributed about the circumference of the pipe. Due to an inclination between the lower ends of the curved upper plate and the support plates, the tightened bolts are placed in both tension and shear.
It is an object of the present invention to provide a pipe shoe which reliably supports a pipe on a pipe rack or other structural support by applying a substantially uniform clamping force to a major circumferential portion of the pipe.
It is a related object of the present invention is to provide a pipe shoe which does not include radially outwardly extending ears to secure the pipe to the pipe shoe.
Yet another object of the invention is an improved method of supporting a pipe from a pipe rack or other structural support, wherein one or more bolts may be tightened to pull the curved upper plate toward the base plate while placing the bolts in both tension and shear.
A significant feature of the present invention is that each of right-side support plate and left-side support plate may be angled with respect to a plane perpendicular to a plane of the base plate. Each support plate is angled away from the centerline of the pipe, such that tightening the bolts pulls the lower ends of the upper plate toward the lower portion of the pipe. More particularly, each of the support plates is preferably angled at from 1xc2x0 to 5xc2x0 with respect to the plane perpendicular to the base plate.
Another feature of the invention is that the same type of attachment mechanism may be used for securing the right-side lower end of the upper plate to the right-side support plate, and the left-side lower end of the upper plate to the left-side support plate.
Another significant feature of the invention is that each of the support plates is positioned radially inward of the respective lower end of the upper plate, thereby reducing the costs of manufacturing the pipe shoe.
Still another significant feature of the invention is that the curved lower plate is configured for planar engagement with the pipe along a circumferential length of from 90xc2x0 to 160xc2x0. Each of the curved lower plate and the curved upper plate may have an arcuate interior surface with a radius substantially conforming to an exterior surface of the pipe.
Yet another feature of the invention is that the pipe shoe may include a front left-side support plate and a front right-side support plate each secured to the base plate, the rear left-side support plate and a rear right-side support plate each affixed to the base plate, and a curved lower plate which extends axially from the front support plates to the rear support plates. A curved front upper plate is provided for engagement with the front support plates and a curved rear upper plate for engagement with a rear support plates.
An advantage of the pipe shoe according to this invention is that conventional components with well known stress and load characteristics are used to fabricate the pipe shoe.
A further advantage of the invention is that the same style pipe shoe may support insulated pipe or bare pipe.
These and further objects, features, and advantages of the present invention will become apparent from the following detailed description wherein reference is made to the figures in the accompanying drawings.